Ubuntu 7.10/Issues/Built In Analog Mic Does Not Work
From DellLinuxWiki
Description: Built-in Analog Microphone Does not work.
Systems Affected: Inspiron 1525n
Impact: Can't record audio.
Fix: Download Dell's custom linux-backports-modules (l-b-m) package linux-backports-modules-2.6.22-14-generic_2.6.22-14.53_i386.deb. This custom l-b-m is not available on any of the Ubuntu repositories, it is only available here.
To install, run:
$ sudo dpkg -i linux-backports-modules-2.6.22-14-generic_2.6.22-14.53_i386.deb
Reboot your system:
$ sudo reboot
Finally, to use the built-in analog microphone, open the gnome volume control:
$ gnome-volume-control
select Edit -> Preferences and select all tracks. Finally, in the the Options tab, set the Digital Input Source to "Analog inputs" and select the first "Input Source" field to "Mic":

NOTE: In some cases, after rebooting, the laptop's volume control buttons and the gnome volume slider will no longer control the builtin speaker's volume.
To fix the system's volume control buttons, run:
$ gnome-sound-properties
in "Default Mixer Tracks", select PCM:

To fix the gnome volume slider, right-click over the volume icon on the top right corner of your screen, select Preferences and then select PCM:

